Yusuf Islam, the British singer formerly known as Cat Stevens, is taking legal action after he was refused entry into the US.

Mr Islam said the decision to deny him entry on grounds of national security was "very serious and wholly unfounded" and he wants an explanation.

His Washington-bound flight was diverted to Maine on Tuesday and he was told to leave the country by the FBI.

He said a legal process had been put in place to find out what had happened.

In a statement Mr Islam, who grew up living above his parents' restaurant in London's West End, said: "Never would I believe that such a thing could happen in the 'land of the free' - unfortunately, it did.

"I was not given (and have still not been given) any explanation as to what it is I am accused of, or why I am now deemed an apparent security threat.

"I was simply told that the order had come from 'on high'.

"We have now initiated a legal process to try to find out exactly what is going on, and to take all necessary steps to undo the very serious, and wholly unfounded, injustice which I have suffered.

"I am a man of peace and denounce all forms of terrorism and injustice; it is simply outrageous for the US authorities to suggest otherwise."

Action was taken against the musician, who converted to Islam and changed his name to Yusuf Islam in the 1970s, after US officials realised he was on a security "watch list".

As a singer Cat Stevens had a string of hits in the 1960s and 1970s, including Moon Shadow, Wild World and Morning Has Broken.

He became interested in rock music in his teens while attending Hammersmith College in London and began performing in 1965 under the name Steve Adams.

He abandoned his music career in the late 1970s.

In 1983 he founded a Muslim school in London and is now an active member of the British Islamic community.